:root {
    --map-height: calc(80vh);
    --t-height: calc(75vh);
}

* {
    padding: 0;
    margin: 0;
}

a {
    padding: 20px;
    color: #FFFFFF;
    height: 20px;
    width: 100px;
}

#nav {
    display: flex;
    border: 1px solid #000000;

    background-color: rgba(0,0,0,1);

    position: sticky;
    top: 0;
    z-index: 2;

    align-items:center;
}
#nav div {
    display: flex;
    flex-direction: column;
}
#nav div h1 {
    color: #FFFFFF;
    margin: 5px 0 5px 5px;
}
#nav div p {
    color: #FFFFFF;
}


#page-head {
    background-color: #000000;
    width: 100%;
    height: 100%;
    position: relative;
    overflow: hidden;

    /* pointer-events: none; */
}
    
#head-video {
    width: 100%;
}
    
#page-head:before {
    position:absolute;
    left: 0;
    top:0;
    display: block;
    width: 100%;
    height: 5em;
    background-color: rgba(0, 0, 0, 0.5);
    content: "我们的家乡";
    font-size: 3em;
    text-align: center;
    /* transition: all 1s ease; */
    transform: translateY(75%);
    color: #FFF;
}

#page-head:after {
    position:absolute;
    left: 0;
    top:0;
    display: block;
    width: 100%;
    height: 100%;
    /* background-color: rgba(0, 0, 0, 0.5); */
    content: "";
    background: url(../src/icons/up-arrow.svg) no-repeat 50% 0;
    background-size: 8%;
    text-align: center;
    transition: all 1s ease;
    transform: translateY(-100%);
    color: #FFF;

}

#page-head:hover:after {
    transform: translateY(82%);
}


#mark {
    margin: 3px 5px 3px 5px;
}

.container {
    margin: 0 0 var(--t-height) 0;

    display: grid;
    justify-items: space-between;
    grid-template-columns: auto auto auto;
    z-index: -2;
}

.map {
    grid-column-start: 1;
    grid-column-end: 4;

    width: 99%;
    height: var(--map-height);
    border: 2px solid #000000;
    text-align: center;

    position: sticky;
    top: 90px;

    z-index: 0;

}

.map .ol-zoom {
    top: 85%;
    left: 95%;
}

.t {
    grid-column-start: 1;
    grid-column-end: 2;

    background-color: rgba(0, 0, 60, 0.6);

    height: var(--t-height);
    width: 400px;
    border: 1px solid #000000;
    margin: 2em 0 var(--map-height) 0;

    position: sticky;
    left: 5%;

    z-index: 1;
}

.t h2  {
    color: #FFFFFF;
    margin: 15px 0 5px 5px;
}

.t p {
    color: #FFFFFF;
    margin: 5px 0 5px 10px;
    padding: 5px;
    line-height: 175%;
}

.img-collection {
    margin: 10px;
    height: calc(30vh);

    display: grid;
    justify-items: center;
    grid-template-columns: auto auto auto;    
}

#img-div {
    height: calc(30vh);

    grid-column-start: 2;
    grid-column-end: 3;

    display: grid;
    justify-items: center;
    align-items: center;
}
#img-div img {
    /* height: inherit; */
    max-width: 90%;
}


.switch {
    margin: calc(12vh) 0 calc(12vh) 0;
    height: calc(6vh);
    width: calc(6vh);
    background-color: rgba(0, 0, 0, 0);
    border: none;
}
#switch-left {
    grid-column-start: 1;
    grid-column-end: 2;
}
#switch-right {
    grid-column-start: 3;
    grid-column-end: 4;
}
.switch img {
    width: inherit;
    height: inherit;
    filter: drop-shadow(3px 3px 3px rgba(255, 255, 255, 0.5));
    transition: 0.5s;
}
.switch :hover {
    filter: drop-shadow(3px 3px 3px rgba(255, 255, 255, 0.3));
}